Hybrid acoustic LC filter cascaded with LC filter

ABSTRACT

Aspects of this disclosure relate to a hybrid acoustic LC filter cascaded with a non-acoustic LC filter. The hybrid acoustic filter can filter a radio frequency signal. The hybrid acoustic LC filter can include acoustic resonators, an inductor, and a capacitor. The inductor and capacitor can be external to an acoustic resonator die. The non-acoustic LC filter includes an LC circuit. Related multiplexers, wireless communication devices, and methods are disclosed.

CROSS REFERENCE TO PRIORITY APPLICATIONS

Any and all applications for which a foreign or domestic priority claimis identified in the Application Data Sheet as filed with the presentapplication are hereby incorporated by reference under 37 CFR § 1.57.This application is a continuation of U.S. patent application Ser. No.16/514,857, filed Jul. 17, 2019 and titled “CASCADED FILTER CIRCUIT WITHHYBRID ACOUSTIC LC FILTER.” U.S. patent application Ser. No. 16/514,857claims the benefit of priority under 35 U.S.C. § 119(e) of U.S.Provisional Patent Application No. 62/700,142, filed Jul. 18, 2018 andtitled “HYBRID ACOUSTIC LC FILTER CASCADED WITH LC FILTER;” U.S.Provisional Patent Application No. 62/700,148, filed Jul. 18, 2018 andtitled “PARALLEL HYBRID ACOUSTIC PASSIVE FILTER;” and U.S. ProvisionalPatent Application No. 62/700,146, filed Jul. 18, 2018 and titled“HYBRID ACOUSTIC LC FILTER WITH HARMONIC SUPPRESSION.” The disclosuresof each of these priority applications are hereby incorporated byreference in their entireties herein.

BACKGROUND Technical Field

Embodiments of this disclosure relate to a hybrid acoustic LC filter.

Description of Related Technology

An acoustic wave filter can include a plurality of acoustic resonatorsarranged to filter a radio frequency signal. Acoustic resonators can bearranged as a ladder filter to filter the radio frequency signal.Example acoustic wave filters include surface acoustic wave (SAW)filters and bulk acoustic wave (BAW) filters. Acoustic wave filters canbe implemented in radio frequency electronic systems. For instance,filters in a radio frequency front end of a mobile phone can includeacoustic wave filters.

An LC filter includes at least an inductor and a capacitor. LC filtersare non-acoustic filters that include passive components. LC filters canfilter radio frequency signals.

Filtering relatively high frequency radio frequency signals and meetingstringent filtering specifications can be difficult. Accordingly,improved filters are desired to filter relatively high frequency signalsand meet performance specifications.

SUMMARY OF CERTAIN INVENTIVE ASPECTS

The innovations described in the claims each have several aspects, nosingle one of which is solely responsible for its desirable attributes.Without limiting the scope of the claims, some prominent features ofthis disclosure will now be briefly described.

One aspect of this disclosure is a cascaded filter for radio frequencyfiltering. The cascaded filter includes a hybrid acoustic LC filter anda non-acoustic LC filter cascaded with the hybrid acoustic LC filter.The hybrid acoustic LC filter is configured to filter a radio frequencysignal. The hybrid acoustic LC filter includes a first acousticresonator on an acoustic resonator die, a second acoustic resonator, acapacitor external to the acoustic resonator die, and an inductorexternal to the acoustic resonator die. The non-acoustic LC filterincludes an LC circuit.

The hybrid acoustic LC filter further can further include a secondinductor in parallel with the second acoustic resonator, in which thesecond acoustic resonator is arranged as a shunt resonator in serieswith the inductor.

The first acoustic resonator and the second acoustic resonator can beshunt resonators. The capacitor and the inductor can be arranged as anLC tank coupled between the first acoustic resonator and the secondacoustic resonator.

The first acoustic resonator can be coupled to a node in a signal pathbetween the LC circuit and both the inductor and the capacitor.

The first acoustic resonator and the second acoustic resonator can bebulk acoustic wave resonators. For example, the first acoustic resonatorand the second acoustic resonator can be film bulk acoustic waveresonators.

The LC circuit of the non-acoustic LC filter can include integratedpassive devices on an integrated passive device die. The inductor of thehybrid acoustic LC filter can be a surface mount inductor. The inductorof the hybrid acoustic LC filter can include a conductive trace of asubstrate. The integrated passive devices can include an LC shuntcircuit and a series LC resonant circuit.

The LC circuit of the non-acoustic LC filter can include a series LCresonant circuit and an LC shunt circuit. The series LC resonant circuitcan include a parallel LC circuit. The LC shunt circuit can includes aseries LC circuit. The LC circuit of the non-acoustic LC filter canfurther include a second shunt series LC circuit.

A passband of the cascaded filter can be set by the non-acoustic LCfilter. The first acoustic resonator can be arranged to providerejection at a frequency band outside of the passband. A lower bound ofthe passband can be at least 3 gigahertz. The passband can spans from atleast 3.3 gigahertz to 4.2 gigahertz.

Another aspect of this disclosure is a multiplexer that includes a firstfilter coupled to a common node and a second filter coupled to thecommon node. The first filter is configured to filter a radio frequencysignal. The first filter includes a hybrid acoustic LC filter and anon-acoustic LC filter cascaded with the hybrid acoustic LC filter. Thehybrid acoustic LC filter includes a first acoustic resonator on anacoustic resonator die, a second acoustic resonator, a capacitorexternal to the acoustic resonator die, and an inductor external to theacoustic resonator die.

The multiplexer can further includes a third filter coupled to thecommon node. The second filter can include a second hybrid acoustic LCfilter. The second filter can include a second non-acoustic LC filter.

Another aspect of this disclosure is a wireless communication devicethat includes an antenna and a radio frequency front end incommunication with the antenna. The radio frequency front end includes afilter configured to filter a radio frequency signal for transmissionvia the antenna. The filter includes a hybrid acoustic LC filter and anon-acoustic LC filter cascaded with the hybrid acoustic LC filter. Thehybrid acoustic LC filter includes acoustic resonators on an acousticresonator die, a capacitor external to the acoustic resonator die, andan inductor external to the acoustic resonator die.

The wireless communication device can be a mobile phone.

Another aspect of this disclosure is a cascaded filter circuit for radiofrequency filtering that includes a hybrid acoustic LC filter, anon-acoustic LC filter including an LC circuit, and a switch configuredto selectively couple the hybrid acoustic LC filter and the non-acousticLC filter. The hybrid acoustic LC filter is configured to filter a radiofrequency signal. The hybrid acoustic LC filter includes an acousticresonator on an acoustic resonator die, a capacitor external to theacoustic resonator die, and an inductor external to the acousticresonator die.

The cascaded filter circuit can further includes a second non acousticLC filter, in which the switch is configured to couple the hybridacoustic LC filter and the non-acoustic LC filter in a first state, andin which the switch is configured to couple the hybrid acoustic LCfilter and the second non-acoustic LC filter in a second state. Thenon-acoustic LC filter can be a transmit filter and the secondnon-acoustic LC filter can be a receive filter.

The cascaded filter circuit can further include a second hybrid acousticLC filter, in which the switch is configured to couple the hybridacoustic LC filter and the non-acoustic LC filter in a first state, andin which the switch is configured to couple the second hybrid acousticLC filter and the non-acoustic LC filter in a second state.

The hybrid acoustic LC filter can further includes a second inductor inparallel with the acoustic resonator, in which the acoustic resonator isarranged as a shunt resonator in series with the inductor.

The hybrid acoustic LC filter can further include a second acousticresonator. The first acoustic resonator and the second acousticresonator can be shunt resonators. The capacitor and the inductor can bearranged as an LC tank between the acoustic resonator and the secondacoustic resonator. The hybrid acoustic LC filter can further include asecond inductor in series with the first acoustic resonator and a thirdinductor in series with the second acoustic resonator.

The acoustic resonator can be a bulk acoustic wave resonator.

The LC circuit of the non-acoustic LC filter can include integratedpassive devices of an integrated passive device die. The inductor of thehybrid acoustic LC filter can be a surface mount inductor. The inductorof the hybrid acoustic LC filter can include a conductive trace of asubstrate.

A passband of a cascaded filter that includes the non-acoustic LC filterand the hybrid acoustic LC filter can be set by the non-acoustic LCfilter. A lower bound of the passband can be at least 3 gigahertz.

Another aspect of this disclosure is a method of filtering a radiofrequency signal. The method includes coupling, with a switch, a hybridacoustic LC filter and a non-acoustic LC filter. The hybrid acoustic LCfilter includes an acoustic resonator on an acoustic resonator die, acapacitor external to the acoustic resonator die, and an inductorexternal to the acoustic resonator die. The method also includesfiltering a radio frequency signal while the hybrid acoustic LC filterand the non-acoustic filter are coupled together.

The method can further include decoupling, with the switch, the hybridacoustic LC filter from the non-acoustic LC filter; and coupling, withthe switch, the hybrid acoustic LC filter and a second non acoustic LCfilter. The method can further include providing, with a poweramplifier, the radio frequency signal to the non-acoustic LC filter; andamplifying, with a low noise amplifier, a filtered signal provided bythe second non-acoustic filter.

The filtering can include providing, using the acoustic resonator of thehybrid acoustic LC filter, rejection outside of a passband of a filterthat includes the hybrid acoustic LC filter and the non-acoustic LCfilter.

The radio frequency signal can have a frequency in a range from 3gigahertz to 5 gigahertz.

Another aspect of this disclosure is a wireless communication devicethat includes an antenna and a radio frequency front end incommunication with the antenna. The radio frequency front end includes afilter configured to filter a radio frequency signal for transmissionvia the antenna. The filter includes a hybrid acoustic LC filter, anon-acoustic LC filter, and a switch configured to selectively couplethe hybrid acoustic LC filter and the non-acoustic LC filter. The hybridacoustic LC filter includes an acoustic resonator on an acousticresonator die and an LC component external to the acoustic resonatordie.

The wireless communication device can be a mobile phone.

Another aspect of this disclosure is a parallel hybrid acoustic passivefilter that includes a first sub-filter and a second sub-filter coupledin parallel with the first sub-filter. The first sub-filter includes afirst acoustic resonator and a first non-acoustic passive component. Thesecond sub-filter includes a second acoustic resonator and a secondnon-acoustic passive component. The first sub-filter and the secondsub-filter are together arranged to filter a radio frequency signal.

The first sub-filter and the second sub-filter can be together arrangedas a band pass filter having a passband. A frequency response of theparallel hybrid acoustic passive filter can have a first sub-passbandcorresponding to the first sub-filter, a second sub-passbandcorresponding to the second sub-filter, and a notch at a notch frequencybetween the first sub-passband and a second sub-passband.

The first sub-filter and the second sub-filter can be together arrangedas a band stop filter having a stop band. The band stop filter can havea notch in the stop band.

The first sub-filter can includes bulk acoustic wave resonators thatinclude the acoustic resonator.

The first non-acoustic passive component can include a first inductorand a second inductor, in which the first inductor is in parallel withthe acoustic resonator, and in which the acoustic resonator is arrangedas a shunt resonator that is in series with the second inductor.

The first sub-filter can further include an additional acousticresonator, in which the first acoustic resonator and the additionalacoustic resonator are shunt resonators, and in which the firstnon-acoustic passive component includes a capacitor and an inductorarranged as an LC tank coupled between the first acoustic resonator andthe additional acoustic resonator.

The second non-acoustic passive component can include an integratedpassive device.

The first sub-filter and the second sub-filter can have differentpassbands. A lower bound of a passband of the parallel hybrid acousticpassive filter can be at least 2 gigahertz.

Another aspect of this disclosure is a multiplexer with a parallelhybrid acoustic passive filter. The multiplexer includes a first filtercoupled to a common node and a second filter coupled to the common node.The first filter is configured to filter a radio frequency signal. Thefirst filter includes a first sub-filter in parallel with a secondsub-filter. The first sub-filter includes a first acoustic resonator anda first non-acoustic passive component. The second sub-filter includes asecond acoustic resonator and a second non acoustic passive component.

The first filter can be a band pass filter. A frequency response of thefirst filter can have a first sub-passband corresponding to the firstsub-filter, a second sub-passband corresponding to the secondsub-filter, and a notch at a notch frequency between the firstsub-passband and a second sub-passband. The second filter can be a bandstop filter.

The first filter can be a band stop filter having a stop band and anotch in the stop band.

The second filter can include another acoustic resonator and anothernon-acoustic passive component.

The first filter can have a first passband, the second filter can have asecond passband, and the first passband can have a lower edge that is ata higher frequency than an upper edge of the second passband.

The multiplexer can further include a third filter coupled to the commonnode.

The multiplexer can further include a shared filter in series betweenthe first filter and the common node, in which the shared filter is alsoin series between the second filter and the common node. The sharedfilter can be a high pass filter.

Another aspect of this disclosure is a wireless communication devicethat includes a radio frequency front end an antenna in communicationwith the radio frequency front end. The radio frequency front endincludes a filter configured to filter a radio frequency signal. Thefilter includes a first sub-filter in parallel with a second sub filter.The first sub-filter includes a first acoustic resonator and a firstnon-acoustic passive component. The second sub-filter includes a secondacoustic resonator and a second non acoustic passive component.

Another aspect of this disclosure is a multiplexer with a hybridacoustic passive filter. The multiplexer includes a plurality of filtersconfigured to filter respective radio frequency signals, a shared filtercoupled between each of the plurality of filters and a common node, anda radio frequency filter coupled to the common node. Each filter of theplurality of filters has a different passband. At least a first filterof the plurality of filters includes acoustic resonators and anon-acoustic passive component.

The plurality of filters can includes the first filter, a second filter,and a third filter. The first filter can be a first band pass filterhaving a first passband. The second filter can be a second band passfilter having a second passband. The third filter can be a band stopfilter having a stop band that includes the first passband and thesecond passband.

The shared filter can be a high pass filter. The radio frequency filtercan be a low pass filter.

The shared filter can be a non-acoustic LC filter. The shared filter caninclude second acoustic resonators and an LC component.

The non-acoustic passive component can include an inductor arranged inparallel with a first acoustic resonator of the acoustic resonators.

The acoustic resonators can be embodied on an acoustic resonator die.The non-acoustic passive component can include an inductor external tothe acoustic resonator die and a capacitor external to the acousticresonator die.

A second filter of the plurality of filter can include second acousticresonators and a second non-acoustic passive component. The first filtercan have a first passband and the second filter can have a secondpassband. The first and second passbands can both be within a frequencyrange from 2 gigahertz to 5 gigahertz. The first and second passbandscan both be within a frequency range from 2 gigahertz to 3 gigahertz.

The multiplexer can be arranged as a quadplexer.

Another aspect of this disclosure is wireless communication device thatincludes an antenna and a multiplexer in communication with the antenna.The multiplexer includes a plurality of filters configured to filterrespective radio frequency signals, a shared filter coupled between eachof the plurality of filters and a common node, and a radio frequencyfilter coupled to the common node. The plurality of filters includes afirst filter that includes acoustic resonators and a non-acousticpassive component.

A second filter of the plurality of filter can include second acousticresonators and a second non-acoustic passive component. The wirelesscommunication device can be configured to support a carrier aggregationat the common node. The carrier aggregation can includes a first carrierand a second carrier, in which the first carrier is within a firstpassband of the first filter, and in which the second carrier is outsideof the first passband and a second passband of the second filter.

Another aspect of this disclosure is a multiplexer with hybrid acousticpassive filters. The multiplexer includes a plurality of filtersincluding a first filter and a second filter having different radiofrequency passbands, a shared high pass filter coupled between each ofthe plurality of filters and a common node, and a low pass filtercoupled to the common node. The first filter includes first acousticresonators and a first LC circuit. The second filter includes secondacoustic resonators and a second LC circuit.

The plurality of filters can further include a band stop filter having astop band that includes the passbands of the first and second filters.

Another aspect of this disclosure is a hybrid acoustic LC filter withharmonic suppression. The hybrid acoustic LC filter includes a hybridpassive/acoustic filter configured to filter a radio frequency signaland a non-acoustic LC filter cascaded with the hybrid passive/acousticfilter. The hybrid passive/acoustic filter includes acoustic resonatorsand a non-acoustic passive component. The non-acoustic LC filter isconfigured to suppress a harmonic of the radio frequency signal.

The non-acoustic LC filter can be a notch filter. A frequency responseof the notch filter can have a notch corresponding to a second harmonicof the radio frequency signal. A frequency response of the notch filtercan have two notches corresponding to different harmonics of the radiofrequency signal.

The non-acoustic LC filter can be a low pass filter.

The non-acoustic LC filter can include integrated passive devices of anintegrated passive device die.

The acoustic resonators can include bulk acoustic wave resonators.

The non-acoustic passive component can include a first inductor and asecond inductor. The acoustic resonators can include a first shuntacoustic resonator arranged in series with the first inductor and inparallel with the second inductor.

The acoustic resonators can include a first shunt acoustic resonator anda second shunt acoustic resonator. The non-acoustic passive componentcan include an LC tank coupled between the first shunt acousticresonator and the second shunt acoustic resonator.

Another aspect of this disclosure is a multiplexer that includes a firstfilter configured to filter a radio frequency signal and a second filtercoupled to the first filter at a common node. The first filter includesa hybrid passive/acoustic filter and a non-acoustic LC filter cascadedwith the hybrid passive/acoustic filter. The hybrid passive/acousticfilter includes acoustic resonators and a non-acoustic passivecomponent. The non-acoustic LC filter is configured to suppress aharmonic of the radio frequency signal.

The second filter can include second acoustic resonators and a secondnon-acoustic passive component. The first filter can be a mid-bandfilter and the second filter can be a high band filter. The multiplexercan further include a low band filter coupled to the first filter andthe second filter at the common node.

The non-acoustic LC filter can include integrated passive devices of anintegrated passive device die.

The non-acoustic passive component can include a first inductor and asecond inductor. The acoustic resonators can include a first shuntacoustic resonator arranged in series with the first inductor and inparallel with the second inductor.

The acoustic resonators can include a first shunt acoustic resonator anda second shunt acoustic resonator. The non-acoustic passive componentcan include an LC tank coupled between the first shunt acousticresonator and the second shunt acoustic resonator.

The acoustic resonators can include bulk acoustic wave resonators.

Another aspect of this disclosure is a wireless communication devicethat includes radio frequency front end and an antenna in communicationwith the radio frequency front end. The radio frequency front endincludes a filter configured to filter a radio frequency signal. Thefilter includes a hybrid passive/acoustic filter and an LC filtercascaded with the hybrid passive/acoustic filter. The hybridpassive/acoustic filter includes acoustic resonators and a non-acousticpassive component. The non-acoustic LC filter is configured to suppressa harmonic of the radio frequency signal. The antenna is configured totransmit a filtered version of the radio frequency signal with theharmonic suppressed.

The wireless communication device can be configured as a mobile phone.

The wireless communication device can further include a basebandprocessor and a transceiver, in which the transceiver is incommunication with the radio frequency front end and is also incommunication with the baseband processor.

For purposes of summarizing the disclosure, certain aspects, advantagesand novel features of the innovations have been described herein. It isto be understood that not necessarily all such advantages may beachieved in accordance with any particular embodiment. Thus, theinnovations may be embodied or carried out in a manner that achieves oroptimizes one advantage or group of advantages as taught herein withoutnecessarily achieving other advantages as may be taught or suggestedherein.

The present disclosure relates to U.S. patent application Ser. No.16/514,797, titled “HYBRID ACOUSTIC LC FILTER CASCADED WITH LC FILTER,”filed on Jul. 17, 2019, the entire disclosure of which is herebyincorporated by reference herein. The present disclosure relates to U.S.patent application Ser. No. 16/514,810, titled “PARALLEL HYBRID ACOUSTICPASSIVE FILTER,” filed on Jul. 17, 2019, the entire disclosure of whichis hereby incorporated by reference herein. The present disclosurerelates to U.S. patent application Ser. No. 16/514,883, titled“MULTIPLEXER WITH HYBRID ACOUSTIC PASSIVE FILTER,” filed on Jul. 17,2019, the entire disclosure of which is hereby incorporated by referenceherein. The present disclosure relates to U.S. patent application Ser.No. 16/514,806, titled “HYBRID ACOUSTIC LC FILTER WITH HARMONICSUPPRESSION,” filed on Jul. 17, 2019, the entire disclosure of which ishereby incorporated by reference herein.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of this disclosure will be described, by way of non-limitingexample, with reference to the accompanying drawings.

FIG. 1A is a schematic block diagram of a cascaded filter that includesa hybrid acoustic LC filter and an LC filter according to an embodiment.

FIG. 1B is a schematic block diagram of a radio frequency system thatincludes a cascaded filter in a signal path between a power amplifierand an antenna according to an embodiment.

FIG. 1C is a schematic block diagram of a radio frequency system thatincludes a cascaded filter in a signal path between an antenna and a lownoise amplifier according to an embodiment.

FIG. 2A is a schematic block diagram of a cascaded filter circuit thatincludes a hybrid acoustic LC filter coupled to LC filters by a switchaccording to an embodiment.

FIG. 2B is a schematic block diagram of a cascaded filter circuit thatincludes an LC filter coupled to hybrid acoustic LC filters by a switchaccording to an embodiment.

FIG. 3A is a schematic block diagram of a radio frequency system with acascaded filter circuit according to an embodiment.

FIG. 3B is a schematic block diagram of a radio frequency system with acascaded filter circuit according to another embodiment.

FIG. 3C is a schematic block diagram of a radio frequency system with acascaded filter circuit according to another embodiment.

FIG. 4A is a schematic block diagram of a multiplexer that includes acascaded filter and another filter according to an embodiment.

FIG. 4B is a schematic block diagram of a multiplexer that includes acascaded filter and another filter according to another embodiment.

FIG. 5A is a schematic block diagram that includes a cascaded filter andanother filter coupled to a common mode by a switch according to anembodiment.

FIG. 5B is a schematic block diagram of a multiplexer that includes acascaded filter and another filter coupled to a common mode by a switchaccording to another embodiment.

FIG. 6A is a schematic diagram of a cascaded filter according to anembodiment.

FIG. 6B is a graph of the frequency response of the cascaded filter ofFIG. 6A.

FIG. 7 is a schematic diagram of a cascaded filter according to anotherembodiment.

FIG. 8 is a schematic diagram of a cascaded filter according to anotherembodiment.

FIG. 9 is a schematic diagram of a cascaded filter according to anotherembodiment.

FIG. 10 is a schematic diagram of a cascaded filter according to anotherembodiment.

FIG. 11A is a schematic diagram of a hybrid resonator according to anembodiment.

FIG. 11B is a graph of a frequency response of the hybrid resonator ofFIG. 11A.

FIG. 12 is a schematic diagram of a hybrid resonator according toanother embodiment.

FIG. 13 is a schematic block diagram of a hybrid parallel band passfilter according to an embodiment.

FIG. 14 is a schematic block diagram of a diplexer that includes ahybrid parallel band pass filter according to an embodiment.

FIG. 15 is a schematic block diagram of a triplexer that includes ahybrid parallel band pass filter according to an embodiment.

FIG. 16 is a schematic block diagram of a triplexer that includes ashared high pass filter and a hybrid parallel band pass filter accordingto an embodiment.

FIG. 17 is a schematic block diagram of a quadplexer that includes ashared high pass filter and a hybrid band pass filter according to anembodiment.

FIG. 18 is a schematic diagram of a triplexer that includes a hybridparallel band pass filter according to an embodiment.

FIG. 19A illustrates simulation results of the triplexer of FIG. 18.

FIG. 19B illustrates graphs of simulation results of the triplexer ofFIG. 18 compared to a previous design.

FIG. 20 is a schematic block diagram of a hybrid parallel band stopfilter according to an embodiment.

FIG. 21 is a schematic diagram of a hybrid parallel band stop filteraccording to an embodiment.

FIG. 22 is a graph of a frequency response of the hybrid parallel bandstop filter of FIG. 21.

FIG. 23A is a schematic block diagram of a radio frequency system thatincludes a hybrid acoustic LC filter cascaded with a low pass filteraccording to an embodiment.

FIG. 23B is a schematic block diagram of a radio frequency system thatincludes a hybrid acoustic LC filter cascaded with a second harmonicnotch filter according to an embodiment.

FIG. 24A is a schematic diagram of an example low pass filter.

FIG. 24B is a schematic diagram of another example low pass filter.

FIG. 24C is a schematic diagram of an example second harmonic notchfilter.

FIG. 24D is a schematic diagram of an example harmonic notch filter.

FIG. 24E is a schematic diagram of an example second harmonic notch andlow pass filter.

FIG. 25A is a schematic block diagram of a triplexer that includeshybrid acoustic LC filter cascaded with a low pass filter according toan embodiment.

FIG. 25B is a schematic block diagram of a triplexer that includes ahybrid acoustic LC filter cascaded with a second harmonic notch filteraccording to an embodiment.

FIG. 26 is a schematic diagram of a radio frequency module with atransmit path that includes a filter according to an embodiment.

FIG. 27 is a schematic diagram of a radio frequency module with areceive path that includes a filter according to an embodiment.

FIG. 28 is a schematic diagram of a radio frequency module that includesa filter according to an embodiment.

FIG. 29 is a schematic diagram of a wireless communication device thatincludes a filter according to an embodiment.

FIG. 30 is a schematic diagram of a wireless communication device thatincludes a filter according to another embodiment.

DETAILED DESCRIPTION OF CERTAIN EMBODIMENTS

The following detailed description of certain embodiments presentsvarious descriptions of specific embodiments. However, the innovationsdescribed herein can be embodied in a multitude of different ways, forexample, as defined and covered by the claims. In this description,reference is made to the drawings where like reference numerals canindicate identical or functionally similar elements. It will beunderstood that elements illustrated in the figures are not necessarilydrawn to scale. Moreover, it will be understood that certain embodimentscan include more elements than illustrated in a drawing and/or a subsetof the elements illustrated in a drawing. Further, some embodiments canincorporate any suitable combination of features from two or moredrawings. The headings provided herein are for convenience only and donot necessarily affect the scope or meaning of the claims.

This disclosure relates to filters that include an acoustic componentand a non-acoustic passive component. Certain embodiments relate to ahybrid acoustic LC filter cascaded with an LC filter. Such filters canachieve a relatively wide passband and also meet stringent out-of-bandrejection specifications. Some embodiments relate to filters with anacoustic component and a non-acoustic passive component that arearranged in parallel with each other. Such filters can achieverelatively wide bandwidth and high rejection at stopbands that arerelatively close to a passband without high loss in the passband.Embodiments disclose herein relate to a non-acoustic LC filter cascadedwith a hybrid passive/acoustic filter, in which the non-acoustic LCfilter is arranged to suppress a harmonic of a radio frequency signalprovided by the hybrid passive/acoustic filter. Such filters can achieverelatively high bandwidth and high rejection while suppressingself-created harmonics. Any suitable combination of features of theembodiments disclosed herein can be combined with each other. In variousapplications, two or more embodiments can be implemented together witheach other.

Hybrid Acoustic LC Filter Cascaded with LC Filter

As fifth-generation (5G) wireless communications technology advances,non-acoustic wideband ultra-high band (UHB) filter designs encounterdifficulties with meeting new carrier aggregation specifications. Newcarrier aggregation generally creates more intermodulation frequenciesthat can degrade receiver side sensitivity. Accordingly, carrieraggregation specifications can have more stringent intermodulationdistortion (IMD) rejection specifications for the filter.

LC band pass filters, such as integrated passive device (IPD) band passfilters, have advantages of wide bandwidth and relatively good broad outof band rejections. However, LC band pass filters do not haveparticularly sharp rejections at passband-close frequencies.Non-acoustic passband filters can have significantly worse rolling-offlosses at the passband edge frequencies compared to acoustic wavefilters. This is generally undesirable when high rejection is desiredfor a stopband close to the passband.

Since acoustic resonator filters can provide higher rejection atpassband-close frequencies without high edge rolling off loss due tohigher quality factor (Q) than LC resonators, a passive non-acousticfilter can be cascaded with a hybrid acoustic LC filter to achieve bothwide bandwidth and sharp rejections at the stopbands close to thepassband.

To provide carrier aggregation IMD rejection compliant filters withrelatively sharp rejections at frequencies relatively close to thepassband of the filter, a hybrid acoustic LC filter that can beimplemented. The hybrid acoustic LC filter can be a wideband filter thatincludes one or more capacitors, one or more inductors, and one or moreacoustic resonators. Hybrid acoustic LC filters can include hybridresonators that include an acoustic resonator, at least inductor, and atleast one capacitor.

A hybrid acoustic LC filter can be cascaded with an LC filter to providea relatively low-loss wide passband and also provide relatively sharprejections at frequencies relatively close to the passband of thecascaded filter. The LC filter can include integrated passive devices(IPDs) on an integrated passive device die. The hybrid acoustic LCfilter can include one or more bulk acoustic wave resonators. Thecombination of bulk acoustic wave resonators and LC circuit elements inthe cascaded filter can provide a relatively wide passband and also meetrelatively stringent out-of-band rejection specifications.

Aspects of this disclosure relate to a cascaded filter for filtering aradio frequency signal. The cascaded filter includes a hybrid acousticLC filter and a non-acoustic LC filter cascaded with the hybrid acousticLC filter. The hybrid acoustic LC filter includes acoustic resonators, acapacitor, and an inductor. The non-acoustic LC filter includes an LCcircuit.

Cascaded filters discussed herein can be implemented for variousfrequency bands including wireless bands as long as acoustic resonatorscan be used. As an example, the cascaded filters can have a passband,with a lower frequency bound of at least 2.5 gigahertz (GHz) or at least3 GHz in certain applications. The cascaded filters can have arelatively high upper bound of a passband in certain applications, suchas about 4.5 GHz, about 6 GHz, about 8.5 GHz, or about 10 GHz. Cascadedfilters discussed herein can be implemented in power amplifier modules,diversity receive modules, or any other suitable radio frequency frontend modules. Cascaded filters discussed herein can meet the followingdesign specifications: relatively low insertion loss (IL), relativelysharp frequency cutoff, and relatively strong suppression ofintermodulation frequency and harmonics.

FIG. 1A is a schematic block diagram of a cascaded filter 10 thatincludes a hybrid acoustic LC filter 12 and an LC filter 14 according toan embodiment. The cascaded filter 10 has a first port RF₁ and a secondport RF₂. The hybrid acoustic LC filter 12 and the LC filter 14 arearranged in series with each other between the first port RF₁ and thesecond port RF₂. A radio frequency signal can propagate from the firstport RF₁ to the second port RF₂ in certain applications. A radiofrequency signal can propagate from the second port RF₂ to the firstport RF₁ in various applications.

The hybrid acoustic LC circuit 12 includes one or more acousticresonators, one or more inductors, and one or more capacitors. The oneor more acoustic resonators can be BAW resonators, such as film bulkacoustic wave resonators (FBARs). For instance, the BAW resonators canbe more advantageous for filtering signals having higher frequencies,such as frequencies above 2.5 GHz. The one or more acoustic resonatorscan alternatively or additionally include any other suitable acousticwave resonators, such as one or more surface acoustic wave (SAW)resonators, one or more boundary acoustic wave resonators, and/or one ormore Lamb wave resonators. The hybrid acoustic LC filter 12 can includea capacitor and an inductor external to a die that include the acousticresonator(s). The hybrid acoustic 12 can be a ladder filter. The hybridacoustic filter 12 can be a fixed filter in certain application. A fixedfilter can be implemented with lower complexity than a tunable filter insome instances. The hybrid acoustic LC filter 12 can be tunable in someapplications. When the hybrid acoustic LC filter 12 is tunable, notchesand/or stop bands can be tunable.

The LC circuit 14 includes one or more inductors and one or morecapacitors. The LC circuit 14 can include one or more IPDs, one or moresurface mounted components, one or more passive devices implemented on apackaging substrate, or any suitable combination thereof. Surfacemounted components at some frequencies can have higher quality factorand lower insertion loss than IPDs and passive devices implemented on apackaging substrate. The one or more capacitors can be explicitcapacitor(s) and/or parasitic capacitor(s). The LC circuit 14 can alsoimplement impedance matching.

FIG. 1B is a schematic block diagram of a radio frequency (RF) system 15that includes cascaded filter 10 in a signal path between a poweramplifier 16 and an antenna 17 according to an embodiment. FIG. 1Billustrates that the cascaded filter 10 can be included in a transmitsignal path. In certain applications, the first port RF₁ of the cascadedfilter 10 can be electrically coupled to an output of the poweramplifier 16 and a second port RF₂ of the cascaded filter 10 can beelectrically coupled to the antenna 17. In some applications, the firstport RF₁ of the cascaded filter 10 can be electrically coupled to theantenna 17 and the second port RF₂ of the cascaded filter 10 can beelectrically coupled to the output of the power amplifier 16.

FIG. 1C is a schematic block diagram of an RF system 18 that includes acascaded filter 10 in a signal path between an antenna 17 and a lownoise amplifier 19 according to an embodiment. FIG. 1C illustrates thatthe cascaded filter 10 can be included in a receive signal path. Incertain applications, the first port RF₁ of the cascaded filter 10 canbe electrically coupled to an input of the low noise amplifier 19 and asecond port RF₂ of the cascaded filter 10 can be electrically coupled tothe antenna 17. In some applications, the first port RF₁ of the cascadedfilter 10 can be electrically coupled to the antenna 17 and the secondport RF₂ of the cascaded filter 10 can be electrically coupled to theinput of the low noise amplifier 19.

FIG. 2A is a schematic block diagram of a cascaded filter circuit 20that includes a hybrid acoustic LC filter 12 coupled to LC filters 14Aand 14N by a switch 22 according to an embodiment. The cascaded filtercircuit 20 can share a hybrid acoustic LC filter 12 among a plurality ofLC circuits 14A to 14N. The switch 22 can electrically connect thehybrid acoustic LC filter 12 in series with a selected LC circuit toimplement a cascaded filter. The illustrated switch 22 is a multi-throwradio frequency switch. The switch 22 can electrically couple the hybridacoustic LC filter 12 to a selected LC filter. The switch 22 can haveany suitable number of throws, and the cascaded filter circuit 20 canhave a corresponding number of LC filters 14A to 14N. The illustrated LCfilters 14A and 14N are each coupled to a corresponding port RF₂₁ andRF_(2N), respectively, of the cascaded filter circuit 20. In thecascaded filter circuit 20, the hybrid acoustic LC filter 12 canimplement relatively sharp rejection at frequencies relatively close tothe passband in combination with a selected one or more of the LCfilters 14A to 14N. In certain applications, the hybrid acoustic LCfilter 12 can be tunable to tune the rejection at frequencies relativelyclose the passband for a selected one or more of the LC filters 14A to14N that is electrically coupled thereto.

FIG. 2B is a schematic block diagram of a cascaded filter circuit 25that includes an LC filter 14 coupled to hybrid acoustic LC filters 12Aand 12N by a switch 22 according to an embodiment. The cascaded filtercircuit 20 can share an LC filter 14 among a plurality of hybridacoustic LC circuits 12A to 12N. The switch 22 can electrically connectthe LC filter 14 in series with a selected hybrid acoustic LC circuit toimplement a cascaded filter. The illustrated switch 22 is a multi-throwradio frequency switch. The switch 22 can electrically couple the LCfilter 14 to a selected hybrid acoustic LC filter. The switch 22 canhave any suitable number of throws, and the cascaded filter circuit 25can have a corresponding number of hybrid acoustic LC filters 12A to12N. The illustrated hybrid acoustic LC filters 12A and 12N are eachcoupled to a corresponding port RF₁₁ and RF_(1N), respectively, of thecascaded filter circuit 25.

FIG. 3A is a schematic block diagram of a radio frequency system 30Awith a cascaded filter circuit according to an embodiment. The radiofrequency system 30 is an example system that can implement the cascadedcircuit 20 of FIG. 2A. As illustrated, an antenna 32 is coupled to thehybrid acoustic LC filter 12, the switch 22 is a transmit/receiveswitch, and the LC filters 14A and 14B are connected to a poweramplifier 34 and a low noise amplifier 36, respectively. The cascadedcircuit 25 of FIG. 2B can be implemented in a radio frequency systemthat is similar to the radio frequency system 30A.

FIG. 3B is a schematic block diagram of a radio frequency system 30Bwith a cascaded filter circuit according to another embodiment. FIG. 3Billustrates that LC circuits 14A and 14B can be in different transmitpaths with respective power amplifiers 34A and 34B. Accordingly, thehybrid acoustic LC filter 12 can be included in (a) a cascaded filtercircuit with the LC filter 14A between the power amplifier 34A and theantenna 32 and (b) a cascaded filter circuit with the LC filter 14Bbetween the power amplifier 34B and the antenna 32.

FIG. 3C is a schematic block diagram of a radio frequency system 30Cwith a cascaded filter circuit according to another embodiment. Thecascaded filter of the radio frequency system 30C can be implemented ina diversity receive application, for example. FIG. 3C illustrates thatLC circuits 14A and 14B can be in different receive paths withrespective low noise amplifiers 36A and 36B. Accordingly, the hybridacoustic LC filter 12 can be included in (a) a cascaded filter circuitwith the LC filter 14A between the low noise amplifier 36A and theantenna 32 and (b) a cascaded filter circuit with the LC filter 14Bbetween the low noise amplifier 36B and the antenna 32.

FIG. 4A is a schematic block diagram of a multiplexer 40 that includes acascaded filter and another filter according to an embodiment. Themultiplexer 40 includes a plurality of filters coupled to a common node.As illustrated, a cascaded filter, which includes an LC filter 14 and ahybrid acoustic LC filter 12, and other filter(s) 42 are coupledtogether at the common node. In the multiplexer 40, the LC filter 14 iscoupled to the common node by way of the hybrid acoustic LC filter 12.The multiplexer 40 can be a duplexer with two filters, a triplexer withthree filters, a quadplexer with four filters, etc. The other filter(s)42 can include any suitable number of filters. The other filter(s) 42can include one or more LC filters (e.g., IPD filters), one or moreacoustic wave filters, one or more hybrid acoustic LC filters, the like,or any suitable combination thereof.

FIG. 4B is a schematic block diagram of a multiplexer 45 that includes acascaded filter and another filter according to another embodiment. Themultiplexer 45 is like the multiplexer 40 of FIG. 4A except that thehybrid acoustic LC filter 12 is coupled to the common node by way of theLC filter 14.

A plurality of filters can be in communication with a common node, suchas an antenna node, by way of a switch. FIG. 5A is a schematic diagramof a radio frequency system 50 that includes a cascaded filter andanother filter 42 coupled to a common node by way of a switch 52. Thecascaded filter, the other filter 42, and the switch 52 can implementswitch-plexing. The switch-plexing can implement on-demand multiplexing.

FIG. 5B is a schematic block diagram of a radio frequency system 55 thatincludes a cascaded filter and another filter coupled to a common modeby a switch according to another embodiment. The radio frequency system55 is like the radio frequency system 50 of FIG. 5A except that thehybrid acoustic LC filter 12 and the LC filter 14 are arranged in adifferent order.

FIG. 6A is a schematic diagram of a cascaded filter 60 according to anembodiment. The cascaded filter 60 can be a band pass filter arranged topass radio frequency signals having a frequency above 3 GHz, such asBand 42 signals and/or Band 43 signals and/or Band 48 signals. In suchapplications, the acoustic wave resonators of the filter 60 can be BAWresonators. The filter 60 can be used in 5th generation (5G) wirelesssystems applications. 5G technology can be referred to as 5G New Radio(NR). The cascaded filter 60 includes a hybrid acoustic LC filter 62cascaded with an LC filter 64. The hybrid acoustic LC filter 62 is anexample of the hybrid acoustic LC filter 12. The LC filter 64 is anexample of the LC filter 14.

The hybrid acoustic LC filter 62 includes acoustic resonators A61 andA62; inductors L601, L602, L603, L604, L605, and L606; and capacitorsC601, C602, C603, and C604. The acoustic resonators A61 and A62 can beBAW resonators such as FBARs. In some instances, the acoustic resonatorsA61 and A62 can include a SAW resonator, a temperature compensated SAW(TCSAW) resonator, a boundary acoustic wave resonator, a Lamb waveresonator, the like, or any suitable combination thereof. The inductorsL601, L602, L603, L604, L605, and L606 and capacitors C601, C602, C603,and C604 are LC/non-acoustic components. The LC/non-acoustic componentsof the hybrid acoustic LC filter 62 can be implemented external to a diethat includes the acoustic resonators A61 and A62. The LC/non-acousticcomponents of the hybrid acoustic LC filter 62 can include one or moresurface mount technology (SMT) inductors and/or capacitors. In someinstances, the LC/non-acoustic components of the hybrid acoustic LCfilter 62 can include one or more IPDs and/or one or more inductivetraces on a packaging substrate.

As illustrated, the hybrid acoustic LC filter 62 includes a hybridresonator structure with the inductor L602 in parallel with the acousticresonator A62, in which the inductor L603 is in series with inductor andthe acoustic resonator A62. More details about this hybrid resonatorstructure are provided with reference to FIGS. 11A and 11B. Theillustrated LC filter 62 also includes an LC tank between acoustic nodesat which acoustic resonators A61 and A62 are arranged in series withrespective inductors L603 and L606 in shunt circuits, in which the LCtank includes capacitor C604 and inductor L605. More details about thishybrid resonator structure are proved with reference to FIG. 12.

The LC filter 64 can be a band pass filter. For instance, the LC filter64 can be a Band 42/Band 43 band pass filter. The LC filter 64 includesan IPD part 65 on an IPD die, a packaging substrate part 66 thatincludes traces on the packaging substrate, and SMT part 67 thatincludes SMT components. The IPD part 65 includes IPD capacitors C605,C606, C607, C608, C609, and C610 and IPD inductor L608. The packagingsubstrate part 66 includes inductive traces arranged as inductors L609,L610, L611, and L612. The SMT part 67 includes SMT capacitors C611 andC612.

As illustrated, the LC filter 64 includes bridge capacitors, LC resonantcircuits, coupling capacitors, and a series LC tank. A first bridgecapacitor C610 has a first end coupled to a series LC tank and a secondend coupled to an input node of the LC filter 64. The series LC tankinclude the capacitor C605 and the inductor L608. The first bridgecapacitor C610 is in parallel with the three coupling capacitors C606,C607, and C608.

A first LC resonant circuit is an LC shunt resonant circuit. Asillustrated, the first LC resonant circuit includes a shunt inductorL611 in parallel with a series LC circuit that includes the inductorL612 and capacitor C612. A second bridge capacitor C609 has a first endcoupled to the series LC tank and a second end coupled the first LCresonant circuit. The second bridge capacitor C609 is in parallel withtwo coupling capacitors C606 and C607. A second LC resonant circuit isan LC shunt resonant circuit. As illustrated, the second LC resonantcircuit includes a shunt inductor L609 in parallel with a series LCcircuit that includes inductor L610 and capacitor C611.

A first coupling capacitor C608 is coupled between an input of thefilter and a node at which the first coupling capacitor C608 is coupledto the first LC resonant circuit and a second coupling capacitor C607.The second coupling capacitor C607 is coupled in series between thefirst coupling capacitor C608 and the third coupling capacitor C606. Thesecond coupling capacitor C607 is also coupled between the first LCresonant circuit and the second LC resonant circuit. A third couplingcapacitor C606 is coupled between the series LC tank and a node at whichthe third coupling capacitor C606 is coupled to the second LC resonantcircuit and the second coupling capacitor C607. The illustrated seriesLC tank is a parallel LC circuit.

FIG. 6B is a graph of the frequency response of the cascaded filter 60of FIG. 6A. The illustrated curve represents a frequency response of thecascaded filter of 60 FIG. 6A. The stepped lines represent a designspecification or filter mask. The curve in FIG. 6B indicates that thefrequency response of the cascaded filter 60 of FIG. 6A meets the designspecifications except at 9 GHz. As illustrated, the filter response hastwo nulls created by the shunt acoustic resonators A61 and A62. Thefrequency response has relatively sharp roll off at edges of thepassband. The non-acoustic LC filter 64 of FIG. 6A can provide therelatively large bandwidth. The frequency response has a relatively widebandwidth, which is from around 3.1 GHz to 4.2 GHz in the illustratedfrequency response. Accordingly, the cascaded filter 60 of FIG. 6A canhave a bandwidth of at least 1 GHz. In some other embodiments, cascadedfilters with a hybrid acoustic LC filter cascaded with a non-acoustic LCfilter can have a bandwidth in a range significantly wider thandetermined by an acoustic resonator coupling factor, such as a bandwidthfrom about 3.3 GHz to 4.2 GHz or a bandwidth from about 4.4 GHz to 5GHz.

The cascaded filter 60 of FIG. 6A is an example of a non-acoustic LCfilter cascaded with a hybrid acoustic LC filter. The principles andadvantages discussed herein can be implemented in a variety of otherfilter topologies. Some example filter topologies are shown in FIGS. 7to 10. These filters can be used in 5G applications, for example. Thesefilters include acoustic resonators, such as FBARs, and inductors andcapacitors. The inductors and capacitors can include one or more IPDs,one or more surface mount inductors, one or more surface mountcapacitors, one or more inductive traces on a packaging substrate, thelike, or any suitable combination thereof. The example filters of FIGS.7 to 10 illustrate filters for various applications and designspecifications. Any suitable combination of features of these filterscan be implemented together with each other and/or in accordance withany other principles and advantages discussed herein.

FIG. 7 is a schematic diagram of a cascaded filter 70 according toanother embodiment. The cascaded filter 70 includes a hybrid acoustic LCfilter 72 cascaded with an LC filter 74. The hybrid acoustic LC filter72 is an example of the hybrid acoustic LC filter 12. The LC filter 74is an example of the LC filter 14. The cascaded filter 70 can be areceive filter, for example. The cascaded filter 70 can have a passbandfrom 3.4 GHz to 3.7 GHz in certain applications.

The hybrid acoustic LC filter 72 includes acoustic resonators A71, A72,A73, A74, A75, and A76; capacitors C701, C702, and C703; and inductorsL701, L702, L703, L704, L705, L706, L707, L708, and L709. The acousticresonators A71 to A76 can be BAW resonators. The capacitors C701 to C703can be SMT capacitors. The inductors L701 to L709 can include acombination of SMT inductors and conductive traces of a packagingsubstrate.

The illustrated LC filter 74 includes capacitors C704 and C705 andinductors L710 and L711. In certain embodiments, the LC filter 74 can beimplemented by IPD capacitors and inductors on an IPD die. In some otherembodiments, the LC filter 74 can be implemented by SMT capacitors andinductors on an IPD die.

FIG. 8 is a schematic diagram of a cascaded filter 80 according toanother embodiment. The cascaded filter 80 includes a hybrid acoustic LCfilter 82 cascaded with an LC filter 84. The hybrid acoustic LC filter82 is an example of the hybrid acoustic LC filter 12. The LC filter 84is an example of the LC filter 14. In an embodiment, the cascaded filter80 can be a band pass filter having a passband from around 3.3 GHz to4.2 GHz. According to another embodiment, the cascaded filter can have apassband from 3.4 GHz to 3.7 GHz. The cascaded filter 80 can be areceive filter, for example.

The hybrid acoustic LC filter 82 includes acoustic resonators A81, A82,A83, A84, and A85; capacitors C801 and C802; and inductors L801, L802,L803, L804, L805, and L806. The acoustic resonators A81 to A85 can beBAW resonators. The capacitors C801 and C802 can be SMT capacitors. Theinductors L801 to L805 can include a combination of SMT inductors andconductive traces of a packaging substrate. A hybrid resonator thatincludes the inductors L802 and L803 and acoustic resonators A81, A82,and A83 can function similarly to the hybrid resonator described withreference to FIGS. 11A and 11B. The hybrid ladder structure thatincludes inductors L802 to L805, capacitor C802, and acoustic resonatorsA81 to A85 can function similarly to the hybrid ladder structuredescribed with reference to FIG. 12.

The illustrated LC filter 84 includes capacitors C803, C804, C805, C806,and C807 and inductors L806, L807, L808, and L809. The LC filter 84 caninclude one or more IPDs, one or more SMT components, one or moreconductive traces of a substrate, or any suitable combination thereof.

FIG. 9 is a schematic diagram of a cascaded filter 90 according toanother embodiment. The cascaded filter 90 includes a hybrid acoustic LCfilter 92 cascaded with an LC filter 94. The hybrid acoustic LC filter92 is an example of the hybrid acoustic LC filter 12. The LC filter 94is an example of the LC filter 14. In certain embodiments, the cascadedfilter 90 can include surface mounted passive components except forshunt inductors coupled between acoustic resonators and ground, in whichsuch shunt inductors can be printed traces on a packaging substrate. Assuch, in such embodiments, the cascaded filter 90 does not include anIPD. The cascaded filter 90 can be a receive filter coupled between anantenna switch and a low noise amplifier in certain instances. Thecascaded filter 90 can improve insertion loss relative to previousdesigns. The cascaded filter 90 can be a receive filter.

The hybrid acoustic LC filter 92 includes acoustic resonators A91, A92,and A93; capacitors C901, C902, C903, and C904; and inductors L901,L902, L903, and L904. The acoustic resonators A91 to A93 can be BAWresonators. The capacitors C901 to C904 can be SMT capacitors. Theinductors L901 to L904 can include a combination of SMT inductors andconductive traces of a packaging substrate.

The illustrated LC filter 94 includes capacitors C903, C904, and C905and inductors L905, L906, L907, and L908. The LC filter 94 can includeone or more IPDs, one or more SMT components, one or more conductivetraces of a substrate, or any suitable combination thereof. In oneembodiment, the LC filter 94 consists of SMT inductors and capacitors.

FIG. 10 is a schematic diagram of a cascaded filter according to anotherembodiment. The cascaded filter 100 includes a hybrid acoustic LC filter102 cascaded with an LC filter 104. The hybrid acoustic LC filter 102 isan example of the hybrid acoustic LC filter 12. The LC filter 104 is anexample of the LC filter 14. In certain embodiments, the cascaded filter100 can include IPDs, surface mounted passive components, inductivetraces on a laminate, and FBARs. The cascaded filter 100 can be areceive filter coupled between an antenna switch and a low noiseamplifier in certain instances. The cascaded filter 100 can be a bandpass filter with a passband from about 3.3 GHz to 4.2 GHz. The cascadedfilter 100 is a receive filter in certain embodiments.

The hybrid acoustic LC filter 102 includes acoustic resonators A101,A102, and A103; capacitors C1001 and C1002; and inductors L1001, L1002,L1003, L1004, L1005, and L1006. The acoustic resonators A101 to A103 canbe BAW resonators. The capacitors C1001 and C1002 can include a SMTcapacitor and/or an IPD capacitor. The inductors L1001 to L1006 caninclude one or more SMT inductors, one or more IPD inductors, one ormore conductive traces of a packaging substrate, or any suitablecombination thereof. In an embodiment, the inductors L1001 to L1006include at least SMT inductor, at least one IPD inductor, and at leastone conductive trace of a packaging substrate.

A hybrid resonator that includes the inductors L1002 and L1003 andacoustic resonator A102 can function similarly to the hybrid resonatordescribed with reference to FIGS. 11A and 11B. A hybrid resonator thatincludes the inductors L1005 and L1006 and acoustic resonator A103 canfunction similarly to the hybrid resonator described with reference toFIGS. 11A and 11B. The hybrid ladder structure that includes inductorsL802 to L806, capacitor C1002, and acoustic resonators A102 to A103 canfunction similarly to the hybrid ladder structure described withreference to FIG. 12.

The illustrated LC filter 104 includes capacitors C1003, C1004, C1005,C1006, and C1007 and inductors L1007, L1008, L1009, and L1010. The LCfilter 104 can include one or more IPDs, one or more SMT components, oneor more conductive traces of a substrate, or any suitable combinationthereof. In an embodiment, the LC filter 104 includes at least SMTcomponent, at least one IPD, and at least one conductive trace of apackaging substrate.

The hybrid acoustic LC filters discussed herein can include a variety ofhybrid resonators that include an acoustic wave resonator and anon-acoustic passive component. Example hybrid resonators will bediscussed with reference to FIGS. 11A to 12. These hybrid resonators canbe implemented in association with any suitable embodiments discussedherein.

FIG. 11A is a schematic diagram of a hybrid resonator 110 according toan embodiment. The hybrid resonator 110 includes an acoustic resonator112, a first inductor 114, and a second inductor 116. The acousticresonator 112 is arranged as a shunt resonator. The acoustic resonator112 can be an FBAR, for example. The acoustic resonator 112 can be anyother suitable acoustic resonator. The acoustic resonator 112 is inparallel with the first inductor 114. The acoustic resonator 112 is inseries with the second inductor 116. The combination of the inductors114 and 116 and the acoustic resonator 112 can create a pair of notchesthat are relatively close to passbands without a significant impact ontransmission loss. The notches can be in a range from with about 1.1 GHzto 8.5 GHz from a lower bound or an upper bound of a passband.

FIG. 11B is a graph of a frequency response of the hybrid resonator 110of FIG. 11A. The frequency response illustrates the pair of notchesdiscussed with reference to FIG. 11A. The frequency response alsoillustrates that the simulated hybrid resonator 110 does not introducesignificant transmission loss.

FIG. 12 is a schematic diagram of a hybrid resonator 120 according toanother embodiment. The hybrid resonator 120 is a hybrid ladderstructure. The hybrid resonator 120 includes a first series shuntcircuit, an LC tank, and a second series shunt circuit. The first seriesshunt circuit includes a first acoustic resonator 122 and a firstinductor 123. The second series shunt circuit includes a second acousticresonator 124 and a second inductor 125. The LC tank includes acapacitor 126 in parallel with a third inductor 127. The hybridresonator 120 includes the LC tank between acoustic nodes. This canprovide both inter-resonator impedance matching and a far-end notch in afrequency response of a filter that includes the hybrid resonator 120.The hybrid resonator 120 includes a hybrid ladder structure. The hybridresonator 120 can be used for low pass filters and/or high pass filters,for example. The hybrid resonator 120 is a hybrid ladder topology.

Parallel Hybrid Acoustic Passive Filter

As 5G wireless communications technology advances, new carrieraggregation (CA) specifications can specify more stringentintermodulation distortion (IMD) rejection for a filter. Such new CA caninvolve more multiplexing filters than previous CA. To provide CA IMDrejection compliant filters with sharp rejections at passband-closefrequencies, acoustic-assisted filters can be designed with hybridresonators such as the hybrid acoustic LC resonators to provide arelatively low-loss, wide passband and also have relatively sharprejections at passband-close frequencies. Acoustic resonators cangenerate harmonics when relatively high power is applied. The harmonicsgenerated by a surface acoustic wave device or a bulk acoustic wavedevice can leak to a higher frequency band and/or have an emission overa standard specification.

To provide CA compliant multiplexing filters with sharp rejections atedge band frequencies, hybrid acoustic LC wideband filters can beincluded in some or all of the passband arms. To reduce and/or minimizefilter acoustic die and passive component use, either the hybridacoustic LC filter, an integrated passive devices (IPD) filter, or apassive low pass (LP) or high pass (HP) filter can be shared by two ormore passband arms. In addition, to provide a specific sharp rejectionin high band arm (e.g., at Wi-Fi 2.4 GHz) in a band pass filter (BPF), aparallel hybrid acoustic LC filter can be included. In some instances,the parallel hybrid acoustic LC filter can be cascaded with anotherfilter such as a passive non-acoustic filter.

Hybrid acoustic LC filters with parallel hybrid acoustic LC sub-filtersare disclosed. In an embodiment, a parallel acoustic LC filter includesa first sub-filter configured to filter a radio frequency signal and asecond sub-filter coupled in parallel with the first sub-filter. Thefirst sub-filter includes a first acoustic resonator and a first LCcomponent. The second sub-filter includes a second acoustic resonatorand a second LC component. The parallel hybrid acoustic LC filter can beimplemented in a multiplexer that includes a plurality of filterscoupled together at a common node. A parallel hybrid acoustic filter canimplement any suitable principles and advantages of the acoustic LCcircuits disclosed herein. As one example, a parallel hybrid acoustic LCfilter can include the hybrid resonator 110 of FIG. 11A. As one moreexample, a parallel hybrid acoustic LC filter can include a hybridladder structure 120 of FIG. 12.

Parallel hybrid acoustic LC filters can be band pass filters. Parallelhybrid acoustic LC filters can be band stop filters. A parallel hybridacoustic LC filter can be in a high band path. Such filters can reduceand/or minimize the design complexity. In addition, such filters can beimplemented with fewer passive components and/or in less physical areain certain applications. Parallel hybrid passive filters discussedherein can meet design specifications for high band paths, such asdesired rejections at specific frequencies (e.g., Wi-Fi frequencybands). This can allow the high band path to be shared by a transmitpath and a receive path simultaneously.

A parallel hybrid acoustic LC filter can provide relatively widebandwidth and strong rejection at a particular frequency band. Theparallel hybrid acoustic LC filter can include hybrid filters fordifferent frequency bands in parallel with each other and arranged toprovide strong rejection for another frequency band. As one example, aparallel Band 40 and Band 41 hybrid acoustic LC band pass filter canprovide a bandwidth sufficiently wide to passband 40 and Band 41 signalswhile also providing strong rejection for a 2.4 GHz Wi-Fi frequencyband. In some embodiments, a passive non-acoustic filter can be cascadedwith the parallel hybrid acoustic LC filter to achieve both widebandwidth and sharp rejections in a high band path. According to certainembodiments, a triplexer can be achieved by a parallel hybrid acousticLC filter and two other filters coupled to a common node. For instance,a triplexer for low band (LB)/mid band (MB)/high band (HB) can include aLB filter, a MB filter, and a HB filter implemented by a hybrid acousticLC filter that includes a Band 40 filter in parallel with a Band 41filter. Such a triplexer can effectively serve as a quadplexer tobenefit system level carrier aggregation applications.

FIG. 13 is a schematic block diagram of a hybrid parallel band passfilter 130 according to an embodiment. The parallel hybrid band passfilter 130 includes a first band pass filter 132 and a second band passfilter 134 arranged in parallel with each other. The first band passfilter 132 and the second band pass filter 134 are arranged to filterradio frequency signals. The first band pass filter 132 is a hybridacoustic passive filter that includes a first acoustic resonator and afirst non-acoustic passive component. The first non-acoustic passivecomponent can include at least an inductor and a capacitor. The secondband pass filter 134 can be a hybrid acoustic passive filter thatincludes a second acoustic resonator and a second non-acoustic passivecomponent. The second non-acoustic passive component can include atleast an inductor and a capacitor. The first band pass filter 132 has afirst passband and the second band pass filter 134 has a secondpassband. By including two filters in parallel with each other,bandwidth of the parallel filter can be increased relative to either ofthe individual filters that are included in the parallel filter. Thehybrid parallel band pass filter 130 has a passband that includes thefirst passband and the second passband. A frequency response of thehybrid parallel band pass filter 130 can have a notch in its passbandbetween the first passband and the second passband. The notch can be fora 2.4 GHz Wi-Fi band, for example. A symbol 135 for the parallel hybridband pass filter 130 is also shown in FIG. 13.

Although embodiments are discussed with reference to parallel hybridacoustic LC filters for high band filters, any of the suitableprinciples and advantages discussed herein can be applied to mid bandfilters, low band filters, or any other filters that could benefit fromfeatures discussed herein.

Parallel hybrid acoustic LC filters discussed herein can be implementedin power amplifier modules, diversity receive modules, or any othersuitable radio frequency front end modules.

The parallel hybrid acoustic passive filters discussed herein can beimplemented in multiplexers that include a plurality of filters coupledtogether at a common node. Such multiplexers can include a diplexer, atriplexer, a quadplexer, etc. Any suitable number of filters can becoupled together at a common node in a multiplexer. A plurality offilers can be coupled together at a common node by a multi-throw radiofrequency switch to implement switch-plexing functionality. Some examplemultiplexers that include parallel hybrid acoustic passive filters willbe described with reference to FIGS. 14 to 16. The example multiplexersinclude a parallel hybrid acoustic filter 130 of FIG. 13 and can beimplemented in accordance with any suitable principles and advantages ofthe parallel hybrid acoustic filter 130.

FIG. 14 is a schematic block diagram of a diplexer 140 that includes ahybrid parallel band pass filter 130 according to an embodiment. Thediplexer 140 includes a hybrid parallel band pass filter 130 and asecond filter 144. The parallel hybrid acoustic filter 130 can be a highband filter and the second filter 144 can be a mid-band filter asillustrated. The parallel hybrid acoustic filter 130 and the secondfilter 144 can be coupled together at a common node, such as theillustrated antenna node ANT. The second filter 144 can be a hybridacoustic passive filter, a non-acoustic LC filter, or an acoustic wavefilter. The second filter 144 can be a band stop filter. A stop band ofthe band stop filter can include some or all of the first passband ofthe first band pass filter 132 and/or the second passband of the secondband pass filter 134.

FIG. 15 is a schematic block diagram of a triplexer 150 that includes aand a hybrid parallel band pass filter 130 according to an embodiment.The triplexer 150 includes a hybrid parallel band pass filter 130, asecond filter 154, and a third filter 156. The parallel hybrid acousticfilter 130 can be a high band filter, the second filter 154 can be amid-band filter, and the third filter 156 can be a low band filter asillustrated. The parallel hybrid acoustic filter 130, the second filter154, and the third filter 156 can be coupled together at a common node,such as the illustrated antenna node. The second filter 154 can be ahigh pass and band stop filter. A stop band of the high pass and bandstop filter can include some or all of the first passband of the firstband pass filter 132 and/or the second passband of the second band passfilter 134. The second filter 154 can be a hybrid acoustic LC filter, anon-acoustic LC filter, or an acoustic wave filter. The third filter 156can be a low pass filter. The third filter 156 can be a hybrid acousticLC filter, a non-acoustic LC filter, or an acoustic wave filter. Thethird filter 156 can pass frequencies below the respective passbands ofthe second filter 154 and the hybrid parallel band pass filter 130.

FIG. 16 is a schematic block diagram of a triplexer 160 that includes ashared high pass filter 162 and a hybrid parallel band pass filter 130according to an embodiment. The triplexer 160 is like the triplexer 150of FIG. 15 except that a shared high pass filter 162 is cascaded withboth the hybrid parallel band pass filter 130 and the second filter 144and the second filter 144 is a band stop filter. Accordingly, the sharedhigh pass filter 162 is coupled between the parallel hybrid acousticfilter 130 and the common node. The shared high pass filter 162 is alsocoupled between the second filter 144 and the common node. The sharedhigh pass filter 162 can be an LC filter or a hybrid acoustic LC filter,for example. In an embodiment the shared high pass filter 162 can be anon-acoustic passive filter. Such a shared high pass filter 162 togetherwith the parallel hybrid acoustic filter 130 can achieve relatively widebandwidth and relatively sharp rejections for a high band path.

FIG. 17 is a schematic block diagram of a quadplexer 170 that includes ashared high pass filter 162 and a hybrid band pass filter according toan embodiment. The quadplexer 170 is like the triplexer 160 of FIG. 16except that separate terminals are provided to the first band passfilter 132 and the second band pass filter 134, respectively. This canprovide more freedom in terms of carrier aggregation options. In thequadplexer 170, the first band pass filter 132 and the second band passfilter 134 can receive signals within different frequency band andfilter the respective signals.

FIG. 17 is an example of a multiplexer that includes a hybrid acousticpassive filter. The first band pass filter 132 and the second band passfilter 134 have different passbands and are both coupled to a commonnode (the antenna node ANT in FIG. 17) by way of the shared high passfilter 162. The first band pass filter 132 and/or the second band passfilter 134 can include acoustic resonators and a non-acoustic passivecomponent. The non-acoustic passive component can include an inductorand a capacitor external to a die that includes the acoustic waveresonators. The non-acoustic passive component can include an inductorin parallel with an acoustic resonator of the acoustic resonators. Thefirst band pass filter 132 and/or the second band pass filter 134 caninclude any suitable combination of features of the hybrid acousticpassive filters disclosed herein. In certain embodiments, the first bandpass filter 132 and the second band pass filter 134 each have a passbandwithin a frequency range from 2 gigahertz to 5 gigahertz, such aspassbands within a frequency range from 2 gigahertz to 3 gigahertz.

The band stop filter 144 is coupled to the common node by way of theshared high pass filter 162. The band stop filter 144 includes a stopband that includes the passbands of the first band pass filter 132 andthe second band pass filter 134. The low pass filter 156 is coupled tothe common node.

With the quadplexer 170, certain carrier aggregation performance can beimproved relative to the triplexer 160 of FIG. 16. For example, awireless communication device that includes the quadplexer can support acarrier aggregation at a common node that includes a first carrier and asecond carrier. In this example, the first carrier can be within apassband of the first band pass filter 132 and outside of the passbandof the second band pass filter 134, and the second carrier can beoutside of the passbands of both the first and second band pass filters132 and 134, respectively. By not filtering the first carrier with thesecond band pass filter 134, there can be less insertion lossdegradation in the quadplexer 170 relative to the triplexer 160.

FIG. 18 is a schematic diagram of a triplexer 180 that includes a hybridparallel band pass filter 182 according to an embodiment. In FIG. 18, anexample multiplexer with a hybrid parallel band pass filter isillustrated. As illustrated, the triplexer 180 includes the hybridparallel band pass filter 182, a hybrid acoustic LC filter 184, and anon-acoustic LC filter 186, and a harmonic notch filter 188.

The hybrid parallel band pass filter 182 is an example of the hybridparallel band pass filter 130. The hybrid parallel band pass filer 182is a high band filter in the triplexer 180. The hybrid parallel bandpass filter 182 is an example filter topology of acoustic waveresonators and inductors. As illustrated, a high band signal is providedto the hybrid parallel band pass filter 182 by way of inductors L1801and L1802. The hybrid parallel band pass filter 182 includes a firstsub-filter that includes acoustic resonators A1801, A1802, A1803, A1804,A1805, A1806, A1807, A1808, A1809, and A1810 and inductors L1803, L1804,and L1805. The hybrid parallel band pass filter 182 also includes asecond sub-filter that includes acoustic resonators A1811, A1812, A1813,A1814, A1815, A1816, A1817, A1818, A1819, and A1820 and inductors L1806and L1807. The hybrid parallel band pass circuit 182 includes parasiticcapacitances that are not illustrated in FIG. 18, although theseparasitic capacitances are part of an LC circuit of the hybrid parallelband pass filter 182. Inductors of the hybrid parallel band pass filter182 can include one or more SMT inductors and/or one or more conductivetraces of a substrate. Acoustic resonators of the hybrid parallel bandpass filter 182 can include one or more BAW resonators, such as one ormore FBARs.

The hybrid acoustic LC filter 184 includes acoustic resonators,inductors, and capacitors. As illustrated, the hybrid acoustic LC filter184 includes acoustic resonators A1821, A1822, A1823, A1824, A1825,A1826, A1827, A1828, and A1829; inductors L1808, L1809, L1810, L1811,and L1812; and capacitors C1801 and C1802. The hybrid acoustic LC filter184 can be implemented in accordance with any suitable principles andadvantages of the hybrid acoustic LC filters disclosed herein. Thehybrid acoustic LC filter 184 is a mid-band filter in the triplexer 180.

The non-acoustic LC filter 186 is a low band filter in the triplexer180. The non-acoustic LC filter 186 can be a low pass filter. Such a lowpass filter can be implemented in accordance with any suitableprinciples and advantages of the low pass filters of FIGS. 24A and/or24B, for example.

The harmonic notch filter 188 can provide notches at harmonics of aradio frequency signal to filter out the harmonics. The harmonic notchfilter 188 can be implemented in accordance with any suitable principlesand advantages of the low pass filters of FIG. 24D, for example. Theillustrated harmonic notch filter 188 includes capacitors C1803, C1804,C1805, and C1806 and inductors L1813 and L1814. The harmonic notchfilter 188 can provide notches at two harmonic frequencies.

FIG. 19A illustrates simulation results of the triplexer 180 of FIG. 18.FIG. 19A illustrates the passbands of the filters 182, 184, and 186 ofthe triplexer 180. The low pass filter 186 has a passband indicated by acurve with a solid line. The mid band filter 184 has a passbandindicated by a first dashed curve. The parallel hybrid acoustic bandpass filter 182 passbands indicated by a different dashed curve. Theparallel hybrid acoustic band pass filter 182 has a notch in the middlepart of its passband. This notch can correspond to a frequency rangebetween two different frequency bands that the parallel hybrid acousticband pass filter 182 is arranged to pass. Simulation results indicatethat isolation is improved across mid band and high band filters in thetriplexer 180 compared to previous designs. Reasonable insertion loss ispresent in simulations of the triplexer 180 of FIG. 18 with 9:1 loadpull.

FIG. 19B illustrates graphs of simulation results of the triplexer 180of FIG. 18 compared to a previous design. These simulation resultsindicate that both insertion loss and isolation are improved with thetriplexer 180 compared to the previous design.

Although embodiments of parallel hybrid acoustic filters discussedherein relate to band pass filters, any suitable principles andadvantages of parallel hybrid acoustic filters discussed herein can beapplied to band stop filters. A parallel hybrid acoustic band stopfilter can be implemented as a standalone filter or in a multiplexer.Example parallel hybrid acoustic band stop filters will be discussedwith reference to FIGS. 20 to 22.

FIG. 20 is a schematic block diagram of a hybrid parallel band stopfilter 200 according to an embodiment. The hybrid parallel band stopfilter 200 can create relatively broad-band rejection at close proximityof a passband of another filter without using an LC notch filter, whichcan degrade in-band loss more significantly.

The parallel hybrid band stop filter 200 includes a first band stopfilter 202 and a second band stop filter 204 arranged in parallel witheach other. The first band stop filter 202 and the second band stopfilter 204 are arranged to filter radio frequency signals. The firstband stop filter 202 is a hybrid acoustic passive filter that includes afirst acoustic resonator and a first non-acoustic passive component. Thefirst non-acoustic passive component can include at least an inductorand a capacitor. The second band stop filter 204 is a hybrid acousticpassive filter that includes a second acoustic resonator and a secondnon-acoustic passive component. The second non-acoustic passivecomponent can include at least an inductor and a capacitor. The firstband stop filter 202 has a first stop band and the second band stopfilter 204 has a second stop band. By including two filters in parallelwith each other, stop band of the parallel hybrid band stop filter 200can be increased relative to either of the individual filters 202 or 204that are included in the parallel filter.

The hybrid parallel band stop filter 200 has a stop band that includesthe first stop band and the stop passband. A frequency response of thehybrid parallel band stop filter 200 can have a notch in its stop bandbetween the first stop band and the second stop band. A symbol 205 forthe parallel hybrid band pass filter 200 is also shown in FIG. 20.

FIG. 21 is a schematic diagram of a hybrid parallel band stop filter 210according to an embodiment. The hybrid parallel band stop filter 210 isan example of the hybrid parallel band stop filter 200 of FIG. 20. Thehybrid parallel band stop filer 210 is an example filter topology ofacoustic wave resonators and inductors. The hybrid parallel band stopfiler 210 includes parasitic capacitances that are not illustrated inFIG. 21, although these parasitic capacitances are part of an LC circuitof the hybrid parallel band stop filter 210.

As illustrated, a radio frequency signal can be provided to the hybridparallel band stop filter 210 by way of inductors L2101 and L2102. Thehybrid parallel band stop filter 210 includes a first sub-filter 212that includes acoustic resonators A2101, A2102, A2103, A2104, and A2105and inductors L2103, L2104, L2105, L2106, and L2107. The hybrid parallelband stop filter 210 also includes a second sub-filter 214 that includesacoustic resonators A216, A217, A218, A219, and A220; inductors L2108,L2109, and L2110; and capacitor C2101. Inductors of the hybrid parallelband stop filter 210 can include one or more SMT inductors and/or one ormore conductive traces of a substrate. Acoustic resonators of the hybridparallel band stop filter 210 can include one or more BAW resonators,such as one or more FBARs.

FIG. 22 is a graph of a frequency response of the hybrid parallel bandstop filter 210 of FIG. 21. The frequency response in FIG. 22 shows thata relatively wide stop-band can be achieved with the parallel hybridacoustic band stop filter 210.

Hybrid Acoustic LC Filter with Harmonic Suppression

As 5G wireless communications technology advances, new carrieraggregation (CA) can specify more stringent intermodulation distortion(IMD) rejection for a filter. To provide CA IMD rejection compliantfilters with sharp rejections at the passband-close frequencies,acoustic-assisted filters can be designed with hybrid resonators such asthe hybrid acoustic LC resonators to provide a relatively low-loss, widepassband and also have relatively sharp rejections at passband-closefrequencies. Acoustic resonators can generate harmonics when relativelyhigh power is applied. The harmonics generated by a surface acousticdevice or bulk acoustic device can leak to a higher frequency bandand/or have an emission over a specification for a standard.

Since acoustic resonator filters can generate harmonics at relativelyhigh power, a passive non-acoustic filter can be cascaded with a hybridacoustic LC filter to achieve both hybrid acoustic LC filter rejectionsand to suppress resonator generated harmonics. Accordingly, anon-acoustic LC filter, such as an integrated passive device (IPD)filter, can be cascaded with a hybrid acoustic LC filter to achieve arelatively wide bandwidth and relatively high rejections whilesuppressing self-created harmonics.

Hybrid acoustic LC filters and/or multiplexers discussed herein caninclude a harmonic suppression filter to suppress one or more harmonicfrequencies. The harmonic suppression filter can be a low pass filterand/or a notch filter. Disclosed harmonic suppression filters includenon-acoustic filters. For instance, the harmonic suppression filter canbe an IPD filter. The harmonic suppression filter is cascaded with thehybrid acoustic LC filter. These cascaded filters can be coupled betweena power amplifier and an antenna port. For example, the harmonicsuppression filter can be coupled between an antenna port and the hybridacoustic LC filter.

Aspects of this disclosure relate to a hybrid acoustic LC filter withharmonic suppression. The hybrid acoustic LC includes a hybridpassive/acoustic filter configured to filter a radio frequency signaland a non-acoustic LC filter configured to suppress a harmonic of theradio frequency signal. The hybrid passive/acoustic filter includesacoustic resonators and a non-acoustic passive component. Thenon-acoustic LC filter is cascaded with the hybrid passive/acousticfilter.

The non-acoustic LC filter can be a notch filter. A frequency responseof the notch filter can have a notch corresponding to a second harmonicof the radio frequency signal. A frequency response of the notch filtercan have a notch corresponding to a third harmonic of the radiofrequency signal. The non-acoustic LC filter can be a low pass filter.The non-acoustic LC filter can include integrated passive devices of anintegrated passive device die.

The hybrid passive/acoustic filter can be implemented in accordance withany suitable principles and advantages of any of hybrid resonatorsdisclosed herein. For instance, the hybrid passive/acoustic filter caninclude the hybrid resonator of FIG. 11A and/or the hybrid resonator ofFIG. 12. The acoustic resonators can include bulk wave acousticresonators.

Hybrid acoustic LC filters with harmonic suppression can be implementedin a variety of applications, such as standalone filters, inmultiplexers that include a plurality of filters arranged to filterradio frequency signals, and wireless communication devices such asmobile phones. Hybrid acoustic LC filters with harmonic suppressiondiscussed herein can be implemented in power amplifier modules,diversity receive modules, or any other suitable radio frequency frontend modules.

FIG. 23A is a schematic block diagram of radio frequency system thatincludes a filter 230 that includes a hybrid acoustic LC filter 232cascaded with a low pass filter 233 according to an embodiment. Theradio frequency system also includes a power amplifier 231 and anantenna 234. As illustrated, the hybrid acoustic LC filter 232 canreceive the radio frequency signal from the power amplifier 231. Theradio frequency signal from the power amplifier 231 can have arelatively high power. Acoustic resonators of the hybrid acoustic LCfilter 232 can generate one or more harmonics. The low pass filter 233can filter out such harmonic(s). Accordingly, the filter 230 is a hybridacoustic LC filter with harmonic suppression. As illustrated, the lowpass filter 233 is coupled between an output of the hybrid acoustic LCfilter 232 and the antenna 234. The antenna 234 can transmit a filteredversion of the radio frequency signal provided by the power amplifier231.

The hybrid acoustic LC filter 232 can include acoustic resonators andnon-acoustic passive components. The acoustic resonators can include oneor more bulk acoustic wave resonators such as FBARs, one or more SAWresonators, one or more boundary wave resonators, one or more Lamb waveresonators, the like, or any suitable combination thereof. The hybridacoustic LC filter 232 can include an LC circuit that includes one ormore inductors and one or more capacitors. The one or more capacitorscan include one or more IPD capacitors, one or more surface mountcapacitors, one or more parasitic capacitors, the like, or any suitablecombination thereof. The one or more inductors can include one or moreIPD inductors, one or more surface mount conductors, one or moreinductors implemented as a conductive trace of a packaging substrate,the like, or any suitable combination thereof. The hybrid acoustic LCfilter 232 can be implemented in accordance with any suitable principlesand advantages of hybrid acoustic LC filters disclosed herein. In someinstances, the hybrid acoustic LC filter 232 can include a hybridresonator 110 of FIG. 11A. The hybrid acoustic LC filter 232 can includea hybrid ladder structure 120 of FIG. 12 in certain applications.

In certain applications, the hybrid acoustic LC filter 232 can have apassband from 3.3 GHz to 4.2 GHz. According to some other applications,the hybrid acoustic LC filter 232 can have a passband from 4.4 GHz to 5GHz. The hybrid acoustic LC filter 232 can provide rejection for (a) acarrier aggregation transmit blocker and (b) a continuous-waveout-of-band blocker in various embodiments.

The low pass filter 233 can pass signals below a cutoff frequency andsuppress signals above a cut off frequency. Accordingly, the cutofffrequency of the low pass filter 233 can be selected so as to pass theradio frequency signal from the hybrid acoustic LC filter 232 and tosuppress one or more harmonics of the radio frequency signal. Forinstance, the cutoff frequency could be set to a frequency that is abovethe frequency of the radio frequency signal and below the secondharmonic of the radio frequency signal. In certain embodiments, thehybrid acoustic LC filter 232 is a band pass filter and the cutofffrequency of the low pass filter 233 is above the passband of the bandpass filter and below a second harmonic of the radio frequency signalpassed by the band pass filter.

The low pass filter 233 can be a non-acoustic LC filter. The low passfilter 233 can include one or more capacitors and one or more inductors.The low pass filter 233 can include one or more IPDs, one or moresurface mount passive components, one or more passive components of apackaging substrate such as one or more inductive traces on thepackaging substrate, the like, or any suitable combination thereof.Example circuit topologies for the low pass filter 233 will be discussedwith reference to FIGS. 24A and 24B.

FIG. 23B is a schematic block diagram of a radio frequency system thatincludes a filter 235 that includes a hybrid acoustic LC filter 232cascaded with a harmonic notch filter 236 according to an embodiment.The radio frequency system of FIG. 23B is like the radio frequencysystem of FIG. 23A except that the filter 230 of FIG. 23A is replaced bythe filter 235 in FIG. 23B. The filter 235 is like the filter 230 ofFIG. 23A except that a harmonic notch filter 236 is included in place ofthe low pass filter 233 from the filter 230 of FIG. 23A. As illustrated,the harmonic notch filter 236 is coupled between an output of the hybridacoustic LC filter 232 and the antenna 234.

The harmonic notch filter 236 can have one or more notches in itsfrequency response to filter out one or more corresponding harmonics ofa radio frequency signal from the hybrid acoustic LC filter 232. Thesecond harmonic generated by acoustic resonators of the hybrid acousticLC filter 232 can be the most pronounced harmonic. Accordingly, theharmonic notch filter 236 can be a second harmonic notch filter that hasa notch in its frequency response at a second harmonic. The harmonicnotch filter 236 can have a notch at one or more other harmonics. Incertain embodiments, a harmonic notch filter cascaded with the hybridacoustic LC filter 232 can have two or more notches at any suitableharmonics. As an example, a harmonic notch filter can have notches at asecond harmonic and a third harmonic. With a notch at a harmonic of aradio frequency signal provided by the hybrid acoustic LC filter 232,the harmonic notch filter 236 can suppress the harmonic generated byacoustic resonators of the hybrid acoustic LC filter 232.

The harmonic notch filter 236 can be a non-acoustic LC filter thatincludes one or more capacitors and one or more inductors. The harmonicnotch filter 236 can include one or more IPDs, one or more surface mountpassive components, one or more passive components of a packagingsubstrate such as one or more inductive traces on the packagingsubstrate, the like, or any suitable combination thereof. Examplecircuit topologies for the harmonic notch filter 236 and/or othersuitable harmonic notch filters will be discussed with reference toFIGS. 24C and 24D.

FIG. 24A is a schematic diagram of an example low pass filter 240. Thelow pass filter 240 is an example of the low pass filter 233 of FIG.23A. The low pass filter 240 includes a series inductor L1 and a shuntcapacitor C1 arranged to filter out frequencies above a cutofffrequency. The inductance of the series inductor L1 and the capacitanceof the shunt capacitor C1 can together set the cutoff frequency in thelow pass filter 240.

FIG. 24B is a schematic diagram of another example low pass filter 242.The low pass filter 242 is an example of the low pass filter 233 of FIG.23A. The low pass filter 242 includes series inductors L1 to LN andshunt capacitors C1 to CN. The inductances of the series inductors L1 toLN and the capacitances of the shunt capacitors C1 to CN can togetherset the cutoff frequency in the low pass filter 242.

FIG. 24C is a schematic diagram of an example harmonic notch filter 243.The harmonic notch filter 243 is an example of the harmonic notch filter236 of FIG. 23B. The harmonic notch filter 243 includes a shunt seriesLC circuit. The inductor Ls and a capacitor C1 of the shunt series LCcircuit can set the frequency of the notch. Different impedances of theinductor Ls and the capacitor C1 can together generate a notch atdifferent respective frequencies. The notch can be provided at anysuitable harmonic frequency. For instance, the notch can be set to asecond harmonic of a radio frequency signal provided to the harmonicnotch filter 243. As another example, the notch can be set to a thirdharmonic of a radio frequency signal provided to the harmonic notchfilter 243.

FIG. 24D is a schematic diagram of an example harmonic notch filter 244.The harmonic notch filter 244 is an example of the harmonic notch filter236 of FIG. 23B. The harmonic notch filter 244 includes two shunt seriesLC circuits. A first shunt series LC circuit includes capacitor C1 andinductor Ls1. A second shunt series LC circuit includes capacitor C2 andinductor Ls2. The two shunt series LC circuits can provide notches atdifferent harmonics, such as a second harmonic and a third harmonic.Accordingly, the illustrated harmonic notch filter 244 can providenotches at two different harmonics. The impedances of each shunt seriesLC can set a respective frequency of each notch. Other harmonic notchfilters can provide notches at three or more harmonics.

FIG. 24E is a schematic diagram of an example harmonic notch and lowpass filter 245. The harmonic notch and low pass filter 245 can providea low pass filter that also includes a notch in a frequency response ata harmonic. A shunt series LC circuit can provide the harmonic notch.The shunt series LC circuit includes capacitor C1 and inductor Ls. Aseries inductor L1 together with a shunt capacitor C2 can provide lowpass filter characteristics.

The hybrid acoustic LC filters with harmonic suppression discussedherein can be implemented in multiplexers that include a plurality ofradio frequency filters coupled together at a common node. Examplemultiplexers include diplexers, triplexer, quadplexers, etc. Anysuitable number of filters can be coupled together at a common node in amultiplexer. A plurality of filers can be coupled together at a commonnode by a multi-throw radio frequency switch to implement switch-plexingfunctionality. Some example multiplexers that include a hybrid acousticLC filters with harmonic suppression will be described with reference toFIGS. 25A to 25B. While the multiplexers are triplexers in these exampleembodiments, the principles and advantages associated with suchembodiments can be applied to any other suitable multiplexers. Othersuitable multiplexers include diplexers, quadplexers, etc.

FIG. 25A is a schematic block diagram of a triplexer 250 that includeshybrid acoustic LC filter 232 cascaded with a low pass filter 233according to an embodiment. The triplexer 250 includes the filter 230 ofFIG. 23A, a high band filter 252, and a low band filter 254. The filter230, the high band filter 252, and the low band filter 254 are coupledtogether at a common node, which is an antenna node in the triplexer250. The filter 230 is a mid-band filter in the triplexer 250. The highband filter 252 can be a band pass filter or a high pass filter. Thehigh band filter 252 is arranged to filter high band radio frequencysignals. The high band filter 252 can be a hybrid acoustic LC filterimplemented in accordance with any suitable principles and advantagesdiscussed herein. As one example, the high band filter can includeparallel hybrid acoustic passive filters. In some other embodiments, thehigh band filter 252 can be implemented by any other suitable circuitelements, such as non-acoustic LC circuit elements. The low band filter254 can be a low pass filter or a band pass filter. The low band filter254 is arranged to filter low band radio frequency signals. The low bandfilter 254 can be a hybrid acoustic LC filter implemented in accordancewith any suitable principles and advantages discussed herein. In someother embodiments, the low band filter 254 can be implemented by anyother suitable circuit elements, such as non-acoustic LC circuitelements.

FIG. 25B is a schematic block diagram of a triplexer 255 that includes ahybrid acoustic LC filter 232 cascaded with a harmonic notch filter 236according to an embodiment. The triplexer 255 is like the triplexer 250of FIG. 25A except that the filter 235 is included in place of thefilter 230. The filter 235 includes a harmonic notch filter 236 arrangedto suppress a harmonic in the radio frequency signal provided by thehybrid acoustic LC filter 232. The harmonic notch filter 236 can providenotches for two or more harmonics in some applications. In certainembodiments, a filter of a multiplexer can include a hybrid acoustic LCfilter cascaded with a low pass and harmonic notch filter.

Radio Frequency Modules

The filters disclosed herein can be implemented in a variety of packagedmodules. Some example packaged modules will now be disclosed in whichany suitable principles and advantages of the filters and/ormultiplexers disclosed herein can be implemented. The example packagedmodules can include a package that encloses the illustrated circuitelements. A module that includes a radio frequency component can bereferred to as a radio frequency module. The illustrated circuitelements can be disposed on a common packaging substrate. The packagingsubstrate can be a laminate substrate, for example. FIGS. 26 to 28 areschematic block diagrams of illustrative packaged modules according tocertain embodiments. Any suitable combination of features of thesepackaged modules can be implemented with each other. While filters areillustrated in the example packaged modules of FIGS. 26 to 28, any ofsuch filters can be implemented in a suitable multiplexer.

FIG. 26 is a schematic diagram of a radio frequency module 260 with atransmit path that includes a filter 262 according to an embodiment. Theillustrated module 260 includes the filter 262, a power amplifier 263,and a radio frequency switch 264. The radio frequency module thatincludes a power amplifier can be referred to as a power amplifiermodule. The power amplifier 263 can amplify a radio frequency signal.The radio frequency switch 264 can be a multi-throw radio frequencyswitch. The radio frequency switch 264 can electrically couple an outputof the power amplifier 263 to the filter 262. The filter 262 is atransmit filter arranged to filter a transmit radio frequency signal.The filter 262 can include any suitable combination of features of thefilters disclosed herein. In some other instances, a radio frequencyswitch can selectively electrically connect a transmit signal path to aninput of the power amplifier 263.

FIG. 27 is a schematic diagram of a radio frequency module 270 with areceive path that includes a filter 272 according to an embodiment. Theillustrated module 270 includes the filter 272, a low noise amplifier274, and a radio frequency switch 274. The filter 272 is a receivefilter arranged to filter a received radio frequency signal. The filter272 can include any suitable combination of features of the filtersdisclosed herein. The low noise amplifier 274 can amplify filteredreceived radio frequency signal provided by the filter 272. The radiofrequency switch 274 can electrically couple an output of the low noiseamplifier 274 to a receive path. In certain embodiments, the radiofrequency switch 276 can be a multi-throw radio frequency switcharranged to selectively electrically couple the output of the low noiseamplifier 274 to one or more selected receive paths. In suchembodiments, a radio frequency splitter (not illustrated) can be coupledbetween the low noise amplifier 274 and the radio frequency switch 276.

FIG. 28 is a schematic diagram of a radio frequency module 280 thatincludes a filter 282 according to an embodiment. The illustrated module280 includes one or more filters 282, a radio frequency switch 284, apower amplifier 263, and a low noise amplifier 274. The one or morefilters 282 can include any suitable combination of features of thefilters disclosed herein. The radio frequency switch 284 canelectrically couple the one or more filters 282 to the power amplifier263 and/or the low noise amplifier 274.

Wireless Communication Devices

The filters discussed herein can filter radio frequency signals in awireless communication device. Example wireless communication deviceswill be discussed with reference to FIGS. 29 and 30.

FIG. 29 is a schematic diagram of a wireless communication 290 devicethat includes a filter 293 in a radio frequency front end 292 accordingto an embodiment. The wireless communication device 290 can be anysuitable wireless communication device. For instance, a wirelesscommunication device 290 can be a mobile phone, such as a smart phone.As illustrated, the wireless communication device 290 includes anantenna 291, an RF front end 292 that includes a filter 293, atransceiver 294, a processor 295, a memory 296, and a user interface297. The antenna 291 can transmit RF signals provided by the RF frontend 292. Such RF signals can include carrier aggregation signals. Theantenna 291 can provide received RF signals to the RF front end 292 forprocessing. Such RF signals can include carrier aggregation signals.

The RF front end 292 can include one or more power amplifiers, one ormore low noise amplifiers, RF switches, receive filters, transmitfilters, duplex filters, multiplexers, frequency multiplexing circuits,or any combination thereof. The RF front end 292 can transmit andreceive RF signals associated with any suitable communication standards.The filter 293 can be implemented in accordance with any suitableprinciples and advantages of the filters discussed herein. For instance,the filter 293 can implement any suitable combination of featuresdiscussed with reference to any of FIGS. 1 to 25B. Two or more filtersof the RF front 292 can be implemented in accordance with any suitableprinciples and advantages disclosed herein.

The transceiver 294 can provide RF signals to the RF front end 292 foramplification and/or other processing. The transceiver 294 can alsoprocess an RF signal provided by a low noise amplifier of the RF frontend 292. The transceiver 294 is in communication with the processor 295.The processor 295 can be a baseband processor. The processor 295 canprovide any suitable baseband processing functions for the wirelesscommunication device 290. The memory 296 can be accessed by theprocessor 295. The memory 296 can store any suitable data for thewireless communication device 290. The processor 295 is also incommunication with the user interface 297. The user interface 297 can beany suitable user interface, such as a display.

FIG. 30 is a schematic diagram of a wireless communication device 300that includes a filter 293 in a radio frequency front end 292 and asecond filter 303 in a diversity receive module 302 according to anembodiment. The wireless communication device 300 is like the wirelesscommunication device 290 of FIG. 29, except that the wirelesscommunication device 300 also includes diversity receive features. Asillustrated in FIG. 30, the wireless communication device 300 includes adiversity antenna 301, a diversity module 302 configured to processsignals received by the diversity antenna 301 and including a filter303, and a transceiver 304 in communication with both the radiofrequency front end 292 and the diversity receive module 302. The filter303 can be implemented in accordance with any suitable principles andadvantages of the filters discussed herein. For instance, the filter 303can implement any suitable combination of features discussed withreference to any of FIGS. 1 to 25B. Two or more filters of the diversityreceive module 302 can be implemented in accordance with any suitableprinciples and advantages disclosed herein.

Conclusion

Any of the principles and advantages discussed herein can be applied toother suitable systems, modules, chips, filter assemblies, filters,wireless communication devices, and methods not just to the systems,modules, chips, filter assemblies, filters, wireless communicationdevices, and methods described above. The elements and operations of thevarious embodiments described above can be combined to provide furtherembodiments. Any of the principles and advantages discussed herein canbe implemented in association with radio frequency circuits configuredto process signals having a frequency in a range from about 30 kHz to300 GHz, such as a frequency in a range from about 450 MHz to 8.5 GHz.

Aspects of this disclosure can be implemented in various electronicdevices. Examples of the electronic devices can include, but are notlimited to, consumer electronic products, parts of the consumerelectronic products such as chips and/or packaged radio frequencymodules, electronic test equipment, uplink wireless communicationdevices, personal area network communication devices, etc. Examples ofthe consumer electronic products can include, but are not limited to, amobile phone such as a smart phone, a wearable computing device such asa smart watch or an ear piece, a telephone, a television, a computermonitor, a computer, a router, a modem, a hand-held computer, a laptopcomputer, a tablet computer, a personal digital assistant (PDA), avehicular electronics system such as an automotive electronics system, amicrowave, a refrigerator, a stereo system, a digital music player, acamera such as a digital camera, a portable memory chip, a householdappliance, etc. Further, the electronic devices can include unfinishedproducts.

Conditional language used herein, such as, among others, “can,” “could,”“might,” “may,” “e.g.,” “for example,” “such as” and the like, unlessspecifically stated otherwise or otherwise understood within the contextas used, is generally intended to convey that certain embodimentsinclude, while other embodiments do not include, certain features,elements and/or states. The word “coupled,” as generally used herein,refers to two or more elements that may be either directly coupled toeach other, or coupled by way of one or more intermediate elements.Likewise, the word “connected,” as generally used herein, refers to twoor more elements that may be either directly connected, or connected byway of one or more intermediate elements. Additionally, the words“herein,” “above,” “below,” and words of similar import, when used inthis application, shall refer to this application as a whole and not toany particular portions of this application. Where the context permits,words in the above Detailed Description using the singular or pluralnumber may also include the plural or singular number respectively. Theword “or” in reference to a list of two or more items, that word coversall of the following interpretations of the word: any of the items inthe list, all of the items in the list, and any combination of the itemsin the list.

While certain embodiments have been described, these embodiments havebeen presented by way of example only, and are not intended to limit thescope of the disclosure. Indeed, the novel devices, filters, filterassemblies, chips, methods, apparatus, and systems described herein maybe embodied in a variety of other forms. Furthermore, various omissions,substitutions and changes in the form of the methods, apparatus, andsystems described herein may be made without departing from the spiritof the disclosure. For example, circuit blocks described herein may bedeleted, moved, added, subdivided, combined, and/or modified. Each ofthese circuit blocks may be implemented in a variety of different ways.The accompanying claims and their equivalents are intended to cover anysuch forms or modifications as would fall within the scope and spirit ofthe disclosure.

What is claimed is:
 1. A cascaded filter for radio frequency filtering,the cascaded filter comprising: a hybrid acoustic LC filter configuredto filter a radio frequency signal, the hybrid acoustic LC filterincluding a first acoustic resonator on an acoustic resonator die, asecond acoustic resonator, a capacitor external to the acousticresonator die, and an inductor external to the acoustic resonator die;and a non-acoustic LC filter cascaded with the hybrid acoustic LCfilter, the non-acoustic LC filter including an LC circuit.
 2. Thecascaded filter of claim 1 wherein the hybrid acoustic LC filter furtherincludes a second inductor in parallel with the second acousticresonator, and the second acoustic resonator is arranged as a shuntresonator in series with the inductor.
 3. The cascaded filter of claim 1wherein the first acoustic resonator and the second acoustic resonatorare shunt resonators, and the capacitor and the inductor are arranged asan LC tank coupled between the first acoustic resonator and the secondacoustic resonator.
 4. The cascaded filter of claim 1 wherein the firstacoustic resonator is coupled to a node in a signal path between the LCcircuit and both the inductor and the capacitor.
 5. The cascaded filterof claim 1 wherein the first acoustic resonator and the second acousticresonator are bulk acoustic wave resonators.
 6. The cascaded filter ofclaim 1 wherein the LC circuit of the non-acoustic LC filter includesintegrated passive devices on an integrated passive device die.
 7. Thecascaded filter of claim 6 wherein the inductor of the hybrid acousticLC filter is a surface mount inductor.
 8. The cascaded filter of claim 6wherein the inductor of the hybrid acoustic LC filter includes aconductive trace of a substrate.
 9. The cascaded filter of claim 6wherein the integrated passive devices include an LC shunt circuit and aseries LC resonant circuit.
 10. The cascaded filter of claim 1 whereinthe LC circuit of the non-acoustic LC filter includes a series LCresonant circuit and an LC shunt circuit.
 11. The cascaded filter ofclaim 10 wherein the series LC resonant circuit includes a parallel LCcircuit.
 12. The cascaded filter of claim 1 wherein a passband of thecascaded filter is set by the non-acoustic LC filter.
 13. The cascadedfilter of claim 12 wherein the first acoustic resonator is arranged toprovide rejection at a frequency band outside of the passband.
 14. Thecascaded filter of claim 12 wherein a lower bound of the passband is atleast 3 gigahertz.
 15. The cascaded filter of claim 12 wherein thepassband spans from at least 3.3 gigahertz to 4.2 gigahertz.
 16. Amultiplexer comprising: a first filter coupled to a common node andconfigured to filter a radio frequency signal, the first filterincluding a hybrid acoustic LC filter and a non-acoustic LC filtercascaded with the hybrid acoustic LC filter, the hybrid acoustic LCfilter including a first acoustic resonator on an acoustic resonatordie, a second acoustic resonator, a capacitor external to the acousticresonator die, and an inductor external to the acoustic resonator die;and a second filter coupled to the common node.
 17. The multiplexer ofclaim 16 further comprising a third filter coupled to the common node.18. The multiplexer of claim 16 wherein the second filter includes asecond hybrid acoustic LC filter.
 19. A wireless communication devicecomprising: an antenna; and a radio frequency front end in communicationwith the antenna, the radio frequency front end including a filterconfigured to filter a radio frequency signal for transmission via theantenna, the filter including a hybrid acoustic LC filter and anon-acoustic LC filter cascaded with the hybrid acoustic LC filter, thehybrid acoustic LC filter including acoustic resonators on an acousticresonator die, a capacitor external to the acoustic resonator die, andan inductor external to the acoustic resonator die.
 20. The wirelesscommunication device of claim 19 wherein the wireless communicationdevice is a mobile phone.